Stomatal and non-stomatal limitation to photosynthesis in two trembling aspen (Populus tremuloides Michx.) clones exposed to elevated CO2 and/or O3
Stomatal and non-stomatal limitation to photosynthesis in two trembling aspen (Populus tremuloides Michx.) clones exposed to elevated CO2 and/or O3
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DOI：
10.1046/j.1365-3040.2001.00678.x
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发表时间：
2001-03-01
影响因子：
7.3
通讯作者：
Karnosky, DF
中科院分区：
文献类型：
--
作者：
Noormets, A;Sôber, A;Karnosky, DF
确定两个 2 年生白杨 (Populus tremuloides Michx.) 克隆（216 号，臭氧耐受性和 259 号，臭氧敏感）叶片中的叶片气体交换参数和 1,5-二磷酸核酮糖羧化酶/加氧酶 (Rubisco) 含量，以估计气孔和叶肉对光合作用的相对限制，并确定这些限制如何通过暴露于升高的 CO2 来改变。和/或 O-3。在位于美国威斯康星州莱茵兰德附近的自由空气 CO2 浓缩 (FACE) 设施中，将植物暴露于环境空气（对照）、升高的 CO2 (560 p.p.m.)、升高的 O-3 (55 p.p.b.) 或升高的 CO2 和 O-3 的混合物中。在当前终端和两个侧枝（一个来自上部冠层，一个来自下部冠层）的所有叶子中测量光饱和光合作用和气孔导度，以检测相对气孔限制中可能与年龄相关的变化（叶龄被描述为叶质体时间指数的函数）。在对照和高 CO2 条件下，光合作用随 CO2 升高而增加，而 O-3 则降低。两个克隆中光合作用的相对气孔限制 (I(s)) 约为 10%，在控制下且 O-3 升高。在两个克隆中暴露于升高的CO2+O-3以及在克隆259中暴露于升高的CO2，l(s)甚至进一步降低-至约5%。 Rubisco 含量的相应变化和 C-i/C-a 比率的稳定性表明，响应 CO2 和 O-3 升高的光合作用变化主要是由具有对比 O-3 耐受性的两个白杨无性系中叶肉过程的改变引发的。气孔导度的变化似乎是次要反应，在给定的处理下保持稳定的 C-i，这表明气孔和叶肉过程之间的紧密耦合。
Leaf gas exchange parameters and the content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the leaves of two 2-year-old aspen (Populus tremuloides Michx.) clones (no. 216, ozone tolerant and no. 259, ozone sensitive) were determined to estimate the relative stomatal and mesophyll limitations to photosynthesis and to determine how these limitations were altered by exposure to elevated CO2 and/or O-3. The plants were exposed either to ambient air (control), elevated CO2 (560 p.p.m.) elevated O-3 (55 p.p.b.) or a mixture of elevated CO2 and O-3 in a free air CO2 enrichment (FACE) facility located near Rhinelander, Wisconsin, USA. Light-saturated photosynthesis and stomatal conductance were measured in all leaves of the current terminal and of two lateral branches (one from the upper and one from the lower canopy) to detect possible age-related variation in relative stomatal limitation (leaf age is described as a function of leaf plastochron index). Photosynthesis was increased by elevated CO2 and decreased by O-3 at both control and elevated CO2. The relative stomatal limitation to photosynthesis (l(s)) was in both clones about 10% under control and elevated O-3. Exposure to elevated CO2 + O-3 in both clones and to elevated CO2 in clone 259, decreased l(s) even further - to about 5%. The corresponding changes in Rubisco content and the stability of C-i/C-a ratio suggest that the changes in photosynthesis in response to elevated CO2 and O-3 were primarily triggered by altered mesophyll processes in the two aspen clones of contrasting O-3 tolerance. The changes in stomatal conductance seem to be a secondary response, maintaining stable C-i under the given treatment, that indicates close coupling between stomatal and mesophyll processes.